| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 105 === This research fabricates SnO2 based nanowires by electrospinning. The electrospun nanowires were calcined in air at 300 oC to eliminate part of the polymer template, then further treated in reduced N2 95% + H2 5% or air atmosphere at 550 oC for 2hr. Morphology of the nanowires was examined by SEM. XPS and EDS were used to analyze elemental composition. The fabricated nanowires was used as gas sensor and photoelectrical detector.
Gas sensing experiment was conducted at working temperatures of 50, 100, 150, and 200 oC, respectively. The electrical resistance of the nanowires that were calcined in air at 550 oC was increased upon subjected to NO2. This revealed an n-type gas-sensing property and its sensitivity reached 30 at 150 oC. On the contrary, the nanowires that were reduced at N2 + H2 atmosphere at 550 oC reduced the electrical resistance when brought in contact with NO2, revealing a p-type gas-sensing behavior with a sensitivity reaching 3 at 100 oC.
Photoelectrical conducting experiment was conducted in a dark box by ultraviolet light of wavelength 365 nm. Both could absorb ultraviolet light to raise its conductivity. The nanowires that reduced in N2 + H2 at 550oC raised its conductivity slower and became unsteady after second round of experiment. The nanowires that calcined in air at 550oC , oh the other hand, maintained stable when exposed to ultraviolet light..
The nanowires were examined by the back-gate-MOS measurement for determining the I-V curve over a range of gate voltages and the voltage between source and drain. We confirmed that the nanowires that were reduced in N2 + H2 atmosphere at 550 oC were a p-type semiconductor.
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